Bluetooth (BT) is a short-range wireless communication protocol, for mobile phones, computers, digital cameras, wireless headsets, speakers, keyboards, mice or other input peripherals, and similar devices. BT supports a personal area network (PAN) between a master and a plurality slaves.
BT communication, though, can have a power consumption that in certain types of applications may require compromises in hardware or functionality, or may even render BT impractical. In part to address the power consumption issue, a variation, termed Bluetooth Low Energy or “BTLE” has been developed and adopted in various applications, particularly applications requiring infrequent event-driven transfer of small amounts of data. BILE effectively exploits the infrequent transfer by a corresponding low duty cycle operation, namely, switching at least one of the devices, e.g., a remote sensor, to a sleep mode from which the device(s) are awoken when there is new data to send. Example applications of BTLE include “coin cell” battery-operated sensors and actuators in various medical, industrial, consumer, and fitness applications (also known as “Smart” sensors or actuators), often connecting to devices such as BTLE enabled smart phones, tablets, and lap-tops (also known as “Smart Ready” device).
In an example BTLE operation, a BTLE enabled peripheral device, e.g., a remote sensor, is configured to be awoken by, for example, a timer or sensing event and, upon awakening, to switch to an advertising mode. In the advertising mode the BTLE enabled peripheral device can send a “here I am, with data” advertisement packet. Another device, for example, a BTLE-equipped smart phone, can be configured to periodically switch to an initiator mode and scan for the advertisement packet. When the BTLE-equipped smart phone, in its initiator mode, detects the advertisement packet, it responds with a BTLE protocol connection request packet. The BTLE protocol connection request packet can include attributes that define the BTLE connection. Example attributes can include a frequency hopping sequence, connection interval, and encryption data. Once a connection is established, the BTLE-equipped smart phone switches from the initiator mode to a master device mode, and the BTLE enabled peripheral device switches from its advertiser mode to a slave device mode.
However, in known conventional BTLE, when the transfer of the data associated with the wake-up event is complete, the connection can be terminated. As a result, the connection attributes, for example the frequency hopping sequence and encryption data, as well as application state are lost. Therefore, every time the connection is re-established, the connection and application state must be re-established. Re-establishing the connection and application state can consume power, bandwidth and time. Such consumption can pose problems because, for example, many BTLE enabled peripheral devices may have small battery capacity, or may be packaged or located such that frequent battery replacement is not practical.